INFLAMMATION. 169 



341. Signs of inflammation when established. 



From the consideration of the theory and primary stage of inflamma- 

 tion, we now turn to the consideration of the disease when it has estab- 

 lished itself in a part. 



The principal and usual signs in the part are hypersemia, pain, redness, 

 heat, swelling, and throbbing. The whole or any part of these symptoms 

 may be present. The first, or hyperaemia, has been already dwelt upon. 

 We therefore pass on to the next, namely Pain. 



342. Pain. 



The pain varies very much in different structures. Some are more 

 sensitive than others, but as a general rule the pain is least where the 

 parts are capable of yielding and swelling ; and greatest where they are 

 tense and firm, as in bones, tendons, and ligaments ; or where the part, 

 though soft in itself, is enclosed in unyielding structures, as is the case 

 in regard to the interior parts of the foot. Hence many parts, which 

 are ordinarily insensitive, become exceedingly painful under inflamma- 

 tion, and fever may be expected to supervene when such parts are 

 attacked. The pulse, for instance, is often more affected in laminitis 

 than in many other diseases. 



343. Redness. 



Except in the visible mucous membranes, such as those of the nose, 

 mouth, eyes, &c., we cannot see the redness on account of the hair with 

 which the skin is covered. The redness is due to the greater quantity of 

 blood contained in the vessels of the part affected, and sometimes also 

 at a later stage to extravasation of the colouring matter of the blood 

 into the neighbouring textures. The redness in some cases remains long 

 after the subsidence of the inflammation, on account of the length of 

 time which the vessels, after having been much over-distended, take to 

 regain their tone, and also because the extravasated material is but 

 slowly absorbed. 



344. Heat. 



The temperature of the part is increased both by the greater quantity 

 of blood present in the congested vessels, and also by an actual increase 

 in the temperature of the blood at the part. There must therefore be 

 generation of heat in the inflamed part. This cannot be wondered at 

 when the great changes which are going on in inflamed structures are 

 taken into consideration. 



31-5. Swelling. 



Swelling, which is always most appreciable in the soft external struc- 

 tures, is due in the early stage of the attack to the distension of the 

 blood-vessels ; and it is also much increased in the latter stages by the 

 effusion and exudation which take place through their coats. 



